Vehicle display device

ABSTRACT

A vehicle display device includes a liquid crystal display unit, a temperature sensor that detects a temperature of the liquid crystal display unit, another ECU that acquires vehicle information including a detection result of an external temperature sensor, a heater that heats the liquid crystal display unit, and a microcontroller. The microcontroller controls a heater drive circuit such that the heater is driven at a predetermined first electric power level in cases in which an external temperature at or below 0° C. has been detected by an external temperature sensor and a smart key has been detected by a smart key detector, and such that the heater is driven at a second electric power level greater than the first electric power level in cases in which a door has been opened or a door lock has been unlocked and a temperature at or below 5° C. has been detected by the temperature sensor.

TECHNICAL FIELD

The present invention relates to a vehicle display device that ismounted to a vehicle and that displays various information, images, andthe like.

BACKGROUND ART

Cold cathode fluorescent tubes employed in meter lighting devices,liquid crystal display devices, or the like in an automobile experiencea drop in brightness at low temperatures, and so a heater is provided toheat the tubes to compensate for the drop in brightness at lowtemperatures.

For example, Japanese Patent Application Laid-Open (JP-A) No. H09-48281proposes activating a heater to preheat a cold cathode fluorescent tubewhen unlocking of a door lock of the automobile has been detected,thereby ensuring that automobile lighting equipment that drops inbrightness at low temperatures is sufficiently bright at lowtemperatures.

SUMMARY OF INVENTION Technical Problem

However, a drop in performance at low temperatures is not limited tocold cathode fluorescent tubes. For example, there is an issue withliquid crystals employed in liquid crystal display devices in which theresponse speed of the liquid crystals drops at low temperatures, suchthe display is delayed. A conceivable response thereto is to compensatefor the delay in the response of the liquid crystals by heating theliquid crystals with a heater similarly to in JP-A No. H09-48281.

However in JP-A No. H09-48281, activating the heater when the door lockhas been unlocked results in a large amount of electric power beingconsumed by the heater, and so there is room for improvement withrespect to saving electric power.

In consideration of the above circumstances, an object of the presentinvention is to mitigate a drop in the response speed of a liquidcrystal display device at low temperatures before a vehicle startsrunning, while saving electric power.

Solution to Problem

In order to achieve the above object, a first aspect of the presentdisclosure includes a display section that displays an image, anacquisition section that acquires information indicating at least onetemperature out of a temperature of the display section or an externaltemperature, a heater that heats the display section, and a controllerthat controls driving of the heater. The heater is thereby driven at apredetermined first electric power level in cases in which informationindicating a temperature at or below a predetermined temperature atwhich there is a possibility of a drop in a response speed of thedisplay section is acquired by the acquisition section, and in which apredetermined preheating condition of the heater is satisfied, and suchthat the heater is driven at a second electric power level greater thanthe first electric power level in cases in which a predetermined drivecondition of the heater is satisfied.

In the first aspect of the present disclosure, the display sectiondisplays an image. The display section displays images using, forexample, liquid crystals.

Information indicating at least one temperature out of the temperatureof the display section or the external temperature is acquired by theacquisition section, enabling determination to be made, based on theacquired information indicating temperature, as to whether this is atemperature at which the responsiveness of the display section drops.

The display section is heated by the heater. Thus, for example, at lowtemperatures at which the response speed of the display section drops,the display section is able to be heated by the heater to mitigate thedrop in the response speed.

The controller that controls driving of the heater such that the heateris driven at the predetermined first electric power level in cases inwhich information indicating a temperature at or below a predeterminedtemperature at which there is a possibility of a drop in the responsespeed of the display section is acquired by the acquisition section, andin which the predetermined preheating condition of the heater issatisfied, and such that the heater is driven at the second electricpower level greater than the first electric power level in cases inwhich the predetermined drive condition of the heater is satisfied. Thusdriving the heater using two levels of electric power, enables electricpower to be saved compared to cases in which the heater is driven at asingle electric power level. This enables a drop in the response speedof the display section at low temperatures before the vehicle startsrunning to be mitigated, while saving electric power.

Note that, as in a second aspect of the present disclosure, thepreheating condition may be a condition that is satisfied in cases inwhich a smart key has been detected by a detection section for detectingthe smart key. This enables the heater to be driven prior to an operatorboarding.

Further note that, as in a third aspect of the present disclosure, thedrive condition may be satisfied in cases in which informationindicating a temperature at or below the predetermined temperature isacquired by the acquisition section, and boarding of an operator isdetected by a boarding detection section for detecting operatorboarding. This enables the heater to be driven at the second electricpower level to promote heating of the display section at boarding, atwhich point there is a higher possibility of the display section beingused than when the preheating condition is satisfied.

Moreover, as in a fourth aspect of the present disclosure, thecontroller may further control driving of the heater such that electricpower supplied to the heater to drive the heater is switched to a thirdelectric power level greater than the second electric power level incases in which an automobile ignition switch has been switched on whilethe heater is being driven. It is thereby possible to drive the heaterat the third electric power level, enabling a further saving in electricpower.

Moreover, as in a fifth aspect of the present disclosure, theacquisition section may acquire a detection result from an externaltemperature detection section that continually detects the externaltemperature as the information indicating the external temperature.Namely, acquiring the detection result from the external temperaturedetection section that continually detects the external temperatureenables the temperature to be detected without activating a temperaturesensor or the like provided to the display section, enabling a saving inelectric power.

Moreover, as in a sixth aspect of the present disclosure, the controllermay further control driving of the heater such that driving of theheater is stopped in cases in which the preheating condition is nolonger satisfied when the heater is being driven at the first electricpower level. Wasteful consumption of electric power is therebyprevented, enabling a further saving in electric power.

Moreover, as in a seventh aspect of the present disclosure, thecontroller may further control driving of the heater such that drivingof the heater is stopped in cases in which a temperature higher than thepredetermined temperature has been acquired by the acquisition sectionwhen the heater is being driven at the first electric power level. Thisalso prevents wasteful consumption of electric power, enabling a furthersaving in electric power.

Advantageous Effects of Invention

As explained above, the present invention has the excellent advantageouseffect of enabling a drop in the response speed of a liquid crystaldisplay device at low temperatures before a vehicle starts running to bemitigated, while saving electric power.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a block diagram schematically illustrating a configuration ofa vehicle display device according to an exemplary embodiment.

FIG. 2 is a flowchart illustrating an example of a flow of processingimplemented by a microcontroller of a vehicle display device accordingto the exemplary embodiment.

FIG. 3 is a flowchart illustrating a first modified example of a flow ofprocessing implemented by a microcontroller of a vehicle display deviceaccording to the exemplary embodiment.

FIG. 4 is a flowchart illustrating a second modified example of a flowof processing implemented by a microcontroller of a vehicle displaydevice according to the exemplary embodiment.

DESCRIPTION OF EMBODIMENTS

Detailed explanation follows regarding an exemplary embodiment of thepresent invention, with reference to the drawings. FIG. 1 is a blockdiagram schematically illustrating a configuration of a vehicle displaydevice according to the exemplary embodiment.

As illustrated in FIG. 1, a vehicle display device 10 includes acontroller 12 and a liquid crystal display device 14.

The liquid crystal display device 14 is provided with a heater 20 formitigating a drop in the response speed of liquid crystals at lowtemperatures, and is also provided with a temperature sensor 22 thatdetects the temperature of the liquid crystal display device 14.

The heater 20 is driven by control of the controller 12 so as to heatthe liquid crystal display device 14 when the temperature is low tomitigate a drop in the response speed of the liquid crystals when thetemperature has dropped. One terminal of the heater 20 is grounded andanother terminal of the heater 20 is connected to the controller 12. Thecontroller 12 supplies the heater 20 with electric power from a batteryBT to generate heat.

The temperature sensor 22 detects the temperature of the liquid crystaldisplay device 14 and outputs information indicating the detectedtemperature to the controller 12 to determine whether or not to actuatethe heater 20.

The liquid crystal display device 14 and the controller 12 each includegrounding terminals, which are each connected so as to be grounded tothe chassis ground of the automobile and the like.

The controller 12 is provided with a microcontroller 16 for controllingthe liquid crystal display device 14, and is also provided with a heaterdrive circuit 18 for driving the heater 20.

The heater drive circuit 18, and the temperature sensor 22 provided tothe liquid crystal display device 14, are connected to themicrocontroller 16.

The temperature sensor 22 is connected to the battery BT through apull-up resistor R, and a detection result from the temperature sensor22 is input to the microcontroller 16.

The microcontroller 16 controls the heater drive circuit 18 based on thedetection result from the temperature sensor 22 and so on, therebycontrolling a supply of electric power from the battery BT to the heater20.

The battery BT is connected to the heater drive circuit 18 as a powersource for driving the heater 20. On receiving an activation instructionfrom the microcontroller 16, the heater drive circuit 18 supplieselectric power from the battery BT to the heater 20 to drive the heater20.

Another ECU 24 provided to the vehicle is also connected to themicrocontroller 16. The microcontroller 16 is capable of acquiringvarious information through the other ECU 24. In the present exemplaryembodiment, various information from a smart key detector 26, anexternal temperature sensor 28, a courtesy switch 30, and a door lockswitch 32, all of which are connected to the other ECU 24, is input tothe microcontroller 16 via the other ECU 24.

The smart key detector 26 detects whether or not a smart key in thepossession of an operator is within a detection range. The externaltemperature sensor 28 detects the external temperature. The courtesyswitch 30 is provided to a door opening of the vehicle, and detectsopening and closing of the door. The door lock switch 32 detectsunlocking and locking of a door lock. Note that in the present exemplaryembodiment, the external temperature sensor 28 continually detects theexternal temperature so that the other ECU 24 can execute control basedon the detection result.

In the present exemplary embodiment, at low temperatures at which theresponse speed of the liquid crystal display device 14 drops, themicrocontroller 16 acquires the detection result from the smart keydetector 26 via the other ECU 24 to detect the approach of the operator.The microcontroller 16 then controls the heater drive circuit 18 todrive the heater 20 for preheating prior to the operator boarding.

Note that in cases in which preheating is performed, although apreheating condition is satisfied by smart key detection, it is notcertain that the operator intends to board the vehicle, and so there isa possibility that electric power used for the preheating is wasted dueto the operator moving away from the vehicle after the smart key hasbeen detected. Thus in the present exemplary embodiment, when the smartkey is detected at temperatures at or below a predetermined temperature,a first electric power level, this being is lower than the ratedelectric power level for running the heater 20, is used to drive theheater 20 for preheating. For example, PWM control is used to drive theheater 20, and for the first electric power level, the heater 20 isdriven with a duty ratio of 50%. This enables electric power that iswasted when the operator moves away from the vehicle after the smart keyhas been detected to be kept to a bare minimum.

In the present exemplary embodiment, the microcontroller 16 acquiresinformation from the courtesy switch 30 and the door lock switch 32 viathe other ECU 24 to detect when the operator is boarding. When themicrocontroller 16 detects that the door has been opened or the doorlock has been unlocked while the heater 20 is being driven at the firstelectric power level, in cases in which the temperature is at or below apredetermined temperature, output is increased from the first electricpower level to a second electric power level to drive the heater 20. Forexample, in cases in which PWM control is used to drive the heater 20,the duty ratio is raised from 50%, for the first electric power level,to 80% to increase output and promote heating by the heater 20.Performing preheating in this manner by increasing the level of electricpower driving the heater 20 in steps enables a drop in the responsespeed of the liquid crystal display device at low temperatures beforethe vehicle starts running to be mitigated while also saving electricpower compared to cases in which preheating is performed at a singleelectric power level.

Explanation follows regarding specific processing implemented by themicrocontroller 16 of the vehicle display device 10 according to thepresent exemplary embodiment configured as described above. FIG. 2 is aflowchart illustrating an example of a flow of processing implemented bythe microcontroller 16 of the vehicle display device 10 according to thepresent exemplary embodiment. Note that the processing in FIG. 2 startswhen a smart key in the possession of the operator has been detected bythe smart key detector 26. The processing in FIG. 2 is, for example,implemented by executing a program pre-stored in the microcontroller 16.

When a smart key is detected by the smart key detector 26, at step 100,the microcontroller 16 determines whether or not the externaltemperature is at or below 0° C., this being the predeterminedtemperature range at which there is a possibility that the responsespeed of the liquid crystal display device 14 will drop. For thisdetermination, the microcontroller 16 acquires information indicatingthe external temperature detected by the external temperature sensor 28via the other ECU 24, and determines whether or not the externaltemperature is at or below 0° C., this being the temperature at whichthe response speed of the liquid crystal display device 14 drops. Incases in which determination is affirmative processing transitions tostep 102, and in cases in which determination is negative processingtransitions to step 116. Note that the reference temperature used tomake the determination at step 100 is not limited to 0° C., and anothervalue may be employed therefor.

At step 102, the microcontroller 16 controls the heater drive circuit 18such that the heater 20 is driven at the first electric power level andprocessing transitions to step 104. As described above, the firstelectric power level is a lower electric power level than the ratedelectric power level of the heater 20, and, for example, an electricpower level at which the heater 20 is driven with a duty ratio of 50%.

At step 104, the microcontroller 16 acquires the detection result fromthe smart key detector 26 via the other ECU 24, and determines whetheror not the smart key is being detected. Namely, once the smart key hasbeen detected, the microcontroller 16 determines whether or not thisdetection is continuous, without the operator moving away from thevehicle. In cases in which determination is affirmative processingtransitions to step 106, and in cases in which determination is negativeprocessing transitions to step 118.

At step 106, the microcontroller 16 acquires signals from the courtesyswitch 30 and the door lock switch 32 via the other ECU 24, anddetermines whether or not the door has been opened or the door lock hasbeen unlocked. Namely, at this step, determination is made as to whetheror not the operator is boarding. In cases in which determination isnegative processing returns to step 104 and the above-describedprocessing is repeated. In cases in which determination is affirmativeprocessing transitions to step 108.

At step 108, the microcontroller 16 determines whether or not thetemperature is at or below 5° C., this being a temperature at which theresponse speed of the liquid crystal display device 14 drops, based onthe information indicating the temperature detected by the temperaturesensor 22. In cases in which determination is affirmative processingtransitions to step 110, and in cases in which determination is negativeprocessing transitions to step 118. Note that similarly to step 100,determination may be made based on information indicating the externaltemperature detected by the external temperature sensor 28. Moreover,the reference temperature used to make the determination at step 108 isnot limited to 5° C., and another value may be employed therefor.Although in the present exemplary embodiment the determination referencetemperatures are different at step 100 and step 108, the sametemperature may be employed therefor.

At step 110, the microcontroller 16 determines whether or not the heater20 is being driven at the first electric power level. In thisdetermination, the microcontroller 16 determines whether or not theheater 20 is still being driven at the first electric power level ratherthan whether or not the heater 20 is being driven at the second electricpower level implemented in step 112 described below. In cases in whichdetermination is affirmative processing transitions to step 112, and incases in which determination is negative processing transitions to step114.

At step 112, the microcontroller 16 increases the output driving theheater 20 by controlling the heater drive circuit 18 such that theheater 20 is driven at the second electric power level, processingreturns to step 108, and the above-described processing is repeated. Asdescribed above, the second electric power level is a greater electricpower level than the first electric power level, and, for example, is anelectric power level at which the heater 20 is driven with a duty ratioof 80%.

At step 114, the microcontroller 16 controls the heater drive circuit 18so as to maintain the output driving the heater 20, processing returnsto step 108, and the above-described processing is repeated.

At step 116, the microcontroller 16 determines whether or not the heateris being driven. Namely, the microcontroller 16 determines whether ornot the smart key has been detected, step 102 has been executed, and theheater 20 is in a driven state. In cases in which determination isaffirmative processing transitions to step 118, and in cases in whichdetermination is negative processing ends without any further steps.

At step 118, the microcontroller 16 controls the heater drive circuit 18to stop driving the heater 20, and the processing sequence ends.

Having the microcontroller 16 implement processing in this mannerenables the liquid crystal display device 14 to be preheated at lowtemperatures such that a drop in the response speed of the liquidcrystal can be mitigated prior to the operator boarding. Moreover, sincetwo levels of electric power are used to perform preheating, electricpower can be saved compared to cases in which preheating is performed ata single electric power level. This enables a drop in the response speedof the liquid crystal display device 14 at low temperatures before thevehicle starts running to be mitigated, while also saving electricpower.

In the present exemplary embodiment, prior to starting preheating, thedetection result from the external temperature sensor 28 employed by theother ECU 24 and the like is utilized at step 100 to detect thetemperature without driving the temperature sensor 22, thereby enablingelectric power that would be used to drive the temperature sensor 22 tobe saved.

Preheating is stopped in cases in which the operator moves away withoutboarding after the smart key has been detected and preheating has beenstarted, thereby enabling wasteful electric power consumption to beprevented.

Explanation follows regarding a first modified example of processingimplemented by the microcontroller 16 of the vehicle display device 10according to the present exemplary embodiment. Basic configuration isthe same as in the above exemplary embodiment, and so explanationthereof is omitted. FIG. 3 is a flowchart illustrating the firstmodified example of processing implemented by the microcontroller 16 ofthe vehicle display device 10 according to the present exemplaryembodiment. Note that the same reference numerals are applied toprocessing that is the same as the processing in FIG. 2, and detailedexplanation thereof is omitted.

In the above exemplary embodiment, preheating at the first electricpower level starts when the smart key is detected, and preheating at thesecond electric power level starts when opening of the door or unlockingof the door lock is detected. However, in the first modified example,the preheating conditions at which preheating starts differ.

In the first modified example, preheating at the first electric powerlevel starts when opening of the door or unlocking of the door lock isdetected. Preheating at the second electric power level then starts whenoperator boarding is detected by a seating sensor provided to a vehicleseat, a buckle switch provided to a seatbelt buckle, or the like.Namely, although not illustrated in the drawings, configuration is suchthat information from the seating sensor or the buckle switch isacquired from the other ECU 24 by the microcontroller 16 to performpreheating.

As illustrated in FIG. 3, in the first modified example, steps 103 and105 are performed instead of steps 104 and 106 in FIG. 2, and theprocessing in FIG. 3 is started in cases in which opening of the door orrelease of the door lock has been detected.

Namely, after the microcontroller 16 starts driving of the heater 20 atthe first electric power level at step 102, processing transitions tostep 103, and the microcontroller 16 determines whether or not doorlocking or door closing has been detected while boarding is still yet tobe detected. In this determination, the microcontroller 16 determinesthat boarding is yet to be detected based on signals from the seatingsensor or the buckle switch, and detects door locking or door closingbased on signals from the door lock switch 32 and the courtesy switch30. In cases in which determination is negative processing transitionsto step 105, and in cases in which determination is affirmativeprocessing transitions to the above-described step 118.

At step 105, the microcontroller 16 determines whether or not operatorboarding has been detected. In this determination, the microcontroller16 detects operator boarding based on signals from the seating sensor orthe buckle switch. In cases in which the determination is affirmativeprocessing transitions to the above-described step 108, and in cases inwhich determination is negative processing returns to step 103 and theabove-described processing is repeated.

Advantageous effects similar to that of the above exemplary embodimentare able to be obtained when the microcontroller 16 implementsprocessing in this manner.

Explanation follows regarding a second modified example of processingimplemented by the microcontroller 16 of the vehicle display device 10according to the present exemplary embodiment. Basic configuration isthe same as in the above exemplary embodiment, and so explanationthereof is omitted. FIG. 4 is a flowchart illustrating the secondmodified example of processing implemented by the microcontroller 16 ofthe vehicle display device 10 according to the present exemplaryembodiment. Note that the same reference numerals are applied toprocessing that is the same as the processing in FIG. 2, and detailedexplanation thereof is omitted.

In the above exemplary embodiment and the first modified example,examples were given in which two levels of electric power were used todrive the heater 20 for preheating. However, in the second modifiedexample, three levels of electric power are used to drive the heater 20for preheating. Note that although three levels of electric power areused to drive the heater 20 for preheating in the second modifiedexample, configuration may be such that four or more levels areemployed. For example, the preheating conditions in the above exemplaryembodiment and the preheating conditions in the first modified examplemay be combined such that preheating is performed using four or morelevels of electric power.

As illustrated in FIG. 4, in the second modified example steps 120 and122 are added to the processing in FIG. 2.

Namely, processing transitions to step 120 after executing step 112 orstep 114. At step 120, the microcontroller 16 determines whether or notan ignition switch (IG) has been switched on. In cases in whichdetermination is affirmative processing transitions to step 122, and incases in which determination is negative processing returns to step 108and the above-described processing is repeated.

At step 122, the microcontroller 16 controls the heater drive circuit 18to switch driving of the heater 20 to a third electric power level atfull output (for example, with duty ratio of 100%), processing returnsto step 108, and the above-described processing is repeated.

Thus using three levels of electric power perform preheating alsoenables a drop in the response speed of the liquid crystal displaydevice 14 at low temperatures before the vehicle starts running to bemitigated, while saving electric power.

Note that in the above exemplary embodiment, determination is made atstep 100 as to whether or not the external temperature is at or below 0°C., this being the temperature at which the response speed of the liquidcrystal display device 14 drops, based on a detection result from theexternal temperature sensor 28 acquired from the other ECU 24. However,there is no limitation thereto. For example, determination may be madeas to whether or not the temperature is a temperature at which theresponse speed of the liquid crystal display device 14 drops based on adetection result from the temperature sensor 22, although the electricpower consumed by the liquid crystal display device 14 would increaseaccordingly. Alternatively, detection results may be acquired from boththe temperature sensor 22 and the external temperature sensor 28 todetermine whether or not the respective temperatures are at or below apredetermined temperature.

In the above exemplary embodiment, an example has been given in whichthe liquid crystal display device 14 serves as a display section.However, there is no limitation thereto. Namely, application may be madeto other display devices provided that the response speed of the displaydevice when displaying images drops at low temperatures.

An example has been given in which the processing implemented by themicrocontroller 16 in the above exemplary embodiment is processingimplemented by software. However, there is no limitation thereto. Forexample, the processing may be implemented by hardware, or may beimplemented by a combination of both hardware and software.

The processing implemented by the microcontroller 16 in the aboveexemplary embodiment may also be stored, and distributed, as a programon a storage medium.

The present invention is not limited to the above description, andobviously various other modifications may be implemented within a rangenot departing from the spirit of the present invention.

The entire disclosure of Japanese Patent Application 2016-63933 filedMar. 28, 2016 is incorporated by reference in the present specification.

1-7. (canceled)
 8. A vehicle display device comprising: a displaysection that displays an image; an acquisition section that acquiresinformation indicating at least one of a temperature of the displaysection or an external temperature; a heater that heats the displaysection; and a controller that controls driving of the heater such thatthe heater is driven at a predetermined first electric power level incases in which information indicating a temperature at or below apredetermined temperature at which there is a possibility of a drop in aresponse speed of the display section is acquired by the acquisitionsection, and in which a predetermined preheating condition of the heateris satisfied, and such that the heater is driven at a second electricpower level greater than the first electric power level in cases inwhich a predetermined drive condition of the heater is satisfied,wherein the preheating condition is satisfied in cases in which a smartkey has been detected by a detection section for detecting a smart key.9. The vehicle display device of claim 8, wherein: the drive conditionis satisfied in cases in which information indicating a temperature ator below the predetermined temperature is acquired by the acquisitionsection, and boarding of an operator is detected by a boarding detectionsection for detecting operator boarding.
 10. The vehicle display deviceof claim 8, wherein: the controller further controls driving of theheater such that electric power supplied to the heater to drive theheater is switched to a third electric power level greater than thesecond electric power level in cases in which an automobile ignitionswitch has been switched on while the heater is being driven.
 11. Thevehicle display device of any one of claim 8, wherein: the acquisitionsection acquires a detection result from an external temperaturedetection section that continually detects the external temperature asthe information indicating the external temperature.
 12. The vehicledisplay device of any one of claim 8, wherein: the controller furthercontrols driving of the heater such that driving of the heater isstopped in cases in which the preheating condition is no longersatisfied when the heater is being driven at the first electric powerlevel.
 13. The vehicle display device of any one of claim 8 wherein: thecontroller further controls driving of the heater such that driving ofthe heater is stopped in cases in which a temperature higher than thepredetermined temperature has been acquired by the acquisition sectionwhen the heater is being driven at the first electric power level.